The development of new methods for the enantioselective synthesis of chiral amino alcohols is of continuing importance, since these compounds have interesting biological activity and have enormous potential as chiral ligands in metal-mediated organic reactions. See Blaser, H.-U., Chem. Rev. (1992), 92, 935. It is known that many amino alcohols can be derived from the available amino acids. See Kano, et al., Chem Lett. (1987), 1531 and Kano, et al., Tetrahedron Lett. (1993), 34, 4325. Additionally, several highly stereoselective synthesis of chiral amino alcohols/acids have been reported using chiral auxiliaries. However, these procedures generally involve multi-step reactions. See Mulzer, J; Altenbach, H.-J.; recent example see Oppolzer, W.; Tamura, O.; Sundarababu, G.; Signer, M.; J. Am. Chem. Soc. (1992), 114, 5900. Preparation of the novel compounds of this class requires asymmetric synthesis, preferably using a chiral starting materials. Although advances have been made in this area, (See Lohray et al., Tetrahedron Lett. (1989), 30 2623; Cho et al., Tetrahedron Asymmetry (1992), 3, 341; Fisher et al., Tetrahedron Lett. (1993), 34, 7693; Beardsly Tetrahedron Lett. (1994), 35 1511), new synthetic methods must be developed to access chiral amino alcohols that are not available using current technology.
An attractive approach to the synthesis of chiral amino alcohols involves reduction of keto-oximes. This approach has been used previously in the literature for the preparation of racemic amino alcohols but has not been successfully applied to the enantioselective preparation of cyclic amino alcohols.